[单选题]which of the following are equal以下几个量中相等的是:z0t答案窝(daanwo.com)-大学生作业答案及考资分享平台
① Numbers of different n-bit binary 不同的n位二进制数个数z0t答案窝(daanwo.com)-大学生作业答案及考资分享平台
② The number of legal parentheses matched by n pairs of parenthesesn对小括号所能构成的合法括号匹配个数z0t答案窝(daanwo.com)-大学生作业答案及考资分享平台
③ Numbers of different stack shuffle for {1, 2 .. n}{1, 2 .. n}的不同栈混洗个数z0t答案窝(daanwo.com)-大学生作业答案及考资分享平台
④ Number of operator stack push operations during infix expression evaluation with n operators含n个运算符的中缀表达式求值过程中运算符栈push操作的次数z0t答案窝(daanwo.com)-大学生作业答案及考资分享平台
A①②z0t答案窝(daanwo.com)-大学生作业答案及考资分享平台
B②③z0t答案窝(daanwo.com)-大学生作业答案及考资分享平台
C③④z0t答案窝(daanwo.com)-大学生作业答案及考资分享平台
D②④